The overarching objective of this project is to establish a tissue bank comprised of CNS autopsy material from HIV-infected individuals who are well-characterized neuropsychologically and neuromedically within six months of death. The CNTN represents a collaboration of investigators from the NIMH-funded HIV Neurobehavioral Research Center (HNRC) in San Diego and from four California HIV network sites: University of Southern California/LA County, Cedars-Sinai/University of California, Los Angeles, University of California, Irvine, and the University of California, San Diego. Collectively, these sites follow over 4,300 AIDS patients. The specific aims of the CNTN are: 1) to identify a group of HIV plus persons with advanced disease who agree to be evaluated and consent to autopsy; 2) to characterize these individuals neuromedically and neurobehaviorally using a standardized protocol; 3) to assure that antemortem data are available within 6 months of death; 4) to perform autopsies within 24 hours of death; 5) to characterize the neuropathologic changes associated with HIV; 6) to establish a tissue registry and repository; 7) to establish a database that can support current and future investigator initiated studies integrating antemortem and postmortem data; 8) to establish a process whereby investigators can access tissue and data; and 9) to obtain control tissues. The CNTN consists of a structure and processes for identifying, characterizing and maintaining a cohort of 250 persons with advanced HIV disease in anticipation of their death, of harvesting CNS and other tissues promptly (n=50 annually), of describing, cataloging, and storing these at a central facility in San Diego, and making such materials and data available to investigators to perform scholarly work on neuroAIDS. At the end of 5 years, the CNTN proposes to acquire 209 sets of brain and other tissues from HIV plus individuals for whom there is detailed antemortem characterization. Fifty more brains are expected to be accumulated from other individuals dying with HIV disease, who have interesting neuropathology (e.g., PML), but for whom antemortem information is more limited. We will also accumulate 75 control brains from immunosuppressed patients dying after transplantation or from trauma. The CNTN sites will be coordinated by a core facility in San Diego including a Neuropathology and Banking Unit, a Protocol Monitoring Unit, and a Data Coordinating Unit. An Administrative Unit oversees the operations of the core and network sites, assisted by an internal multi- investigator committee as well as an external Scientific Advisory Board. The significance of the CNTN arises from the demographically and neuropathologically broad representation of cases that will be entered into the network from multiple sites in Southern California. The feasibility of the CNTN is supported by the experience of investigators in implementing standardized protocols of antemortem and postmortem evaluation, as well as the record of this team in successful multidisciplinary and multisite longitudinal investigations.